LOWERING TUNGSTEN RESISTIVITY BY REPLACING TITANIUM NITRIDE WITH TITANIUM SILICON NITRIDE
Semiconductor devices, methods and apparatus for forming the same are provided. The semiconductor device includes a substrate having a source and drain region and a gate electrode stack on the substrate between the source and drain regions. The gate electrode stack includes a conductive film layer on a gate dielectric layer, a refractory metal silicon nitride film layer on the conductive film layer, and a tungsten film layer on the refractory metal silicon nitride film layer. In one embodiment, the method includes positioning a substrate within a processing chamber, wherein the substrate includes a source and drain region, a gate dielectric layer between the source and drain regions, and a conductive film layer on the gate dielectric layer. The method also includes depositing a refractory metal silicon nitride film layer on the conductive film layer and depositing a tungsten film layer on the refractory metal silicon nitride film layer.
1 . A semiconductor device, comprising:
a substrate having a source and drain region; and
a gate electrode stack on the substrate between the source and drain regions; the gate electrode stack comprising:
a conductive film layer on a gate dielectric layer;
a refractory metal silicon nitride film layer on the conductive film layer; and
a tungsten film layer on the refractory metal silicon nitride film layer.
2 . The semiconductor device of claim 1 , wherein the refractory metal silicon nitride film layer is titanium silicon nitride (TiSiN).
3 . The semiconductor device of claim 1 , wherein the tungsten film layer has thickness from about 450 Å to 550 Å and the refractory metal silicon nitride film layer has a thickness from about 20 Å to about 500 Å.
4 . The semiconductor device of claim 2 , wherein the resistivity of the tungsten film layer in the gate electrode stack is between about 10 μohms-cm and 14 μohms-cm.
5 . A method of forming a gate electrode stack, comprising:
positioning a substrate within a processing chamber, wherein the substrate comprises a source and drain region, a gate dielectric layer between the source and drain regions, and a conductive film layer on the gate dielectric layer;
forming a refractory metal silicon nitride film layer on the conductive film layer; and
forming a tungsten film layer on the refractory metal silicon nitride film layer.
6 . The method of claim 5 , wherein the formation processes are performed in-situ.
7 . The method of claim 5 , wherein the refractory metal silicon nitride film layer is titanium silicon nitride (TiSiN).
8 . The method of claim 7 , wherein the resistivity of the tungsten film layer in the gate electrode stack is between about 10 μohms-cm and 14 μohms-cm.
9 . The method of claim 7 , wherein the refractory metal silicon nitride film layer is formed using at least one of a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, and an atomic layer deposition (ALD) process.
10 . A method of depositing a tungsten thin film, comprising:
forming a plasma in a processing region of a chamber using an RF or DC power supply coupled to a titanium silicon alloy target in the chamber, the target having a first surface that is in contact with the processing region of the chamber and a second surface that is opposite the first surface;
delivering energy to a plasma formed in a processing region of a chamber, wherein delivering energy comprises delivering RF power from an RF power supply to a target or delivering DC power from a DC power supply to the target;
rotating a magnetron about the center point of the target,
biasing the substrate support with an RF power supply;
flowing a nitrogen-containing gas into the processing region; and
depositing a tungsten silicon nitride film layer on a substrate positioned on the substrate support in the chamber.
11 . The method of claim 10 , wherein the magnetron is disposed adjacent the second surface of the target, the magnetron comprising:
an outer pole comprising a plurality of magnets; and
an inner pole comprising a plurality of magnets, wherein the outer and inner poles form a closed-loop magnetron assembly.
12 . The method of claim 11 , wherein the ratio of the magnetic fields generated by the outer and inner poles is between about 1.56 and about 0.57.
13 . The method of claim 10 , further comprising heating a substrate support in the chamber.
14 . The method of claim 10 wherein the processing region is pressurized from about 2.5 mTorr to about 6.5 mTorr.
15 . The method of claim 13 , wherein the temperature of the substrate support is from about 50° C. to about 900° C.
16 . The method of claim 10 , wherein the frequency of the RF power supply coupled to the target is greater than the frequency of the RF power supply coupled to the substrate support.
17 . The method of claim 10 , wherein the DC power source is set from 5.0 kW to 50 W and the RF power source coupled to the substrate support is set from 5.0 kW to 50 kW.